1. Field
The disclosure generally relates to a photographing apparatus for preventing and/or reducing light leakage and an image sensor thereof, and for example, to a photographing apparatus for preventing and/or reducing light leakage which occurs in a global shutter and an image sensor thereof.
2. Description of Related Art
In general, an image sensor which generates an image by electrically converting incident light admitted into a lens of a photographing apparatus may be roughly classified into a Charge-Coupled Device (CCD) type image sensor and a Complementary Metal-Oxide Semiconductor (CMOS) type image sensor.
Both of the image sensors maintain proper exposure through an operation of a shutter for controlling light amount based on initiation/terminating of light exposure. The shutter for controlling the light amount is classified into a rolling shutter and a global shutter according to an operating mode.
A rolling shutter type refers to a method of sequentially initiating/terminating the light exposure for respective pixels since an image sensor does not include a storage for storing a charge of a Photo Diode of each pixel. A global shutter type refers to a method of simultaneously initiating the light exposure in entire pixels of an image sensor and simultaneously terminating the light exposure in the entire pixels by using a storage of each pixel after the proper exposure time elapses.
However, in an image sensor of a CMOS-type global shutter, light leakage occurs when the global shutter operates. The light leakage refers to a state where light leaks towards adjacent pixels related to a high-brightness subject area while the charges stored in the entire pixels are stored in a Storage Diode of each pixel at once in a batch or lump, and the charges stored in the Storage Diode of each pixel is read out. Specifically, in case of a pixel which performs a readout operation last, light leakage occurs more significantly in a Storage Diode of the pixel in proportion to a time of performing the readout operation.
Furthermore, a leakage charge caused by the light leakage due to diffraction and diffused reflection of the incident light admitted into a Photo Diode of each pixel may flow into the Storage Diode of each pixel of the image sensor of the CMOS-type global shutter, and a leakage charge caused by the light leakage due to diffraction and diffused reflection of the incident light admitted into a Photo Diode of an adjacent pixel may additionally flow into the Storage Diode of each pixel of the image sensor of the CMOS-type global shutter.